THE amount of goods a couple can accumulate over 44 years living in the same house can be overwhelming. And that is what Wendel and Carolyn Thompson, of Columbia, Md., have been grappling with since January as they prepare to leave their split level and move to a retirement community this month.

Figuring out how to squeeze the contents of a house into a two-bedroom retirement unit nearby in Catonsville, Md., has taken most of their time in recent months. And they’ve had some help. “Declutter ladies,” or downsizing specialists, spend hours with them every week to sort through and pare down their belongings to a more manageable size.

“We’ll get through this. That’s what I tell myself several times every day,” said Mrs. Thompson, 77, a former teacher and Maryland school nutrition program employee, who raised three children in the four-bedroom house. An avid collector of educational materials, games, gifts and other miscellaneous items like teddy bears, she devotes time every day to deciding what goes in the boxes for giving away, the boxes for the new apartment and the boxes for each of her children — and their children.

But, of course, many people do wait — and wait, said Kimberly McMahon, co-owner of Let’s Move, a downsizing and moving specialist in Fulton, Md., whose company is helping Mrs. Thompson and her husband, 78, a former government statistician, to clear out every nook and cranny.

“Downsizing is the hardest because it is emotionally difficult for people to release their history,” said Ms. McMahon. “It’s the worst anxiety associated with any move.”

Her advice is “that nothing should be off limits. Either use it, love it — or leave it.”

Getting rid of furniture and general clutter can be a daunting task. For those with antiques, silver, jewelry and other valuables, Laurene Sherlock, a Bethesda, Md., antiques appraiser, will advise people of outlets like vintage shops, where owners can consign their precious pieces for sale.

But the value of valuables can be cyclical, warned Ms. Sherlock, who noted that 1950s and mid-modern furniture “is hot, and so is Bakelite jewelry, but something else that people love may just not be popular. A lot of younger people just don’t want to be burdened with the tchotchkes.”

While homeowners can amass impressive amounts, the task of clearing out apartments where people have lived for a long time is not any easier, said Ron Shuma, who runs A+ Organizing in New York City.

“I advise going through each drawer and each closet every six months because it’s so much easier,” he said. “But people typically don’t, and that’s where I come in to help people realize what are treasures, and then we get rid of the rest.”

When Hanan Watson, 71, decided to downsize after 35 years in a large two-bedroom Murray Hill apartment, she found that “it is very difficult to sell or even give away many things. Charities can be extremely particular about what they are willing to take.”

She donated some of her art to a nearby community art center, gave some items to relatives and friends and got a lot of assistance from Mr. Shuma in getting rid of larger furniture.

“There are a lot of challenges, for example, the glut of ‘brown furniture” — even good-quality mahogany — which fetches pennies on the dollar,” Mr. Shuma said. “The best thing is for a family member to take it.”

But with careers and young children, fewer 40- or 50-something offspring want to acquire bulkier items or take on the task of sorting and disposing of unwanted goods in their parents’ homes. In the last decade, baby boomers, more used to paying for services than their Depression-era parents, have been increasingly willing to spend money for outsiders to help them pare down their accumulation.

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Jewel Flick, left, of Let's Move, is helping the Thompsons prepare to move. Wendel Thompson, right, checks the value of donated items on a computer.CreditJ.M. Eddins Jr. for The New York Times

The price of such services can vary widely, from $60 an hour in major metropolitan areas except New York City, where the cost can run as high as $200 hourly. In other areas, downsizing help can run $40 an hour. Sorting, packing and moving typically runs from $4,000 and $10,000, depending on the locale, according to specialists.

Despite the cost, the demand for downsizing is strong, according to the National Association of Senior Move Managers. In 2014, the association reported that 50 percent of those contracting for services with its members were older adults, and 30 percent of the initial contacts leading to contracts were from the senior’s family.

An additional 20 percent of business comes from sources like senior housing communities, which have increasingly been establishing programs to help seniors pare back and streamline their belongings before becoming community residents. In 2007, Erickson Living, a major retirement community provider, started a program in Novi, Mich., to advise older adults who had signed up to move to the Fox Run retirement community.

The program, called Erickson Realty and Moving Service, is offered at the 18 Erickson retirement communities around the country, and helps older people with real estate agents, repair people, organizers and movers to smooth their path out of their longtime homes and into smaller spaces.

Last year, the program helped 230 of the 340 people who moved to Erickson properties in Virginia and Maryland, said Sharon Baksa, its regional sales director. The program provides up to $2,000 in relocation expenses — sometimes more.

“We play the role of the surrogate family member,” said Ms. Baksa, who helped start the program in Michigan. “We handle between 1,800 and 1,900 moves a year over all.”

Choosing the retirement community, the Charlestown Retirement Community in Catonsville, helped the Thompsons in Maryland focus on sorting and jettisoning belongings.

“When we set an August date then we knew we had a goal, and we had to meet it,” Mrs. Thompson said.

The downsizing credit was an incentive for the Thompsons, who started in February with a once-a-week visit, for three to four hours, to help sort belongings and get unwanted items out the door. By April, they had increased the declutterer’s schedule to twice a week to meet their target of an August move, and preparing their house for sale by the fall.

They did not have high-end valuables that would warrant an estate sale, but, instead, had one yard sale and then gave away many of their items to family, friends and charities like Goodwill and Habitat for Humanity. Most retirement communities and organizing professionals maintain a list of organizations and what they will accept.

Churches or temples also help. Marc J. Rosenblum, a retired lawyer and economist, has been clearing out his late wife’s belongings and various household goods from his McLean, Va., contemporary home with advice from his synagogue, Temple Rodef Shalom.

“They provided suggestions for where to allocate items, for destinations like a homeless shelter in Bailey’s Crossroads, Va., and a nearby thrift store,” said Mr. Rosenblum, 78. He first consulted a downsizing specialist, which, he said, “saved a lot of time, and helped me pick up some good ideas, including a furniture auctioneer.”

He handled the downsizing task largely on his own, but others like the Thompsons say they welcome the help and the prompting for what many see as an onerous, time-consuming job.

Even with the help, “it’s one step at a time,” said Mr. Thompson. “And I don’t see the end yet.”

For people thinking about beginning the task, here are some ideas from Kimberly McMahon, of Let’s Move..

■ Write some organizing time on your calendar.

■ Set a timer to get started.

■ Start small, even if it’s matching up a cup with a saucer.

■ Get a friend to help.

■ Fill a trash bag once a week.

■ Call and book a donation pickup for the next day.

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A version of this article appears in print on , on Page B4 of the New York edition with the headline: Moving to a Smaller Home, and Decluttering a Lifetime of Belongings. Order Reprints | Today’s Paper | Subscribe